1. Technical Field
Embodiments of the present invention relate generally to cryotherapy and brachytherapy and, more particularly, to combined cryotherapy and brachytherapy methods and devices.
2. Description of Related Art
Several approaches to cancer treatment are known. The most common and effective approaches include: surgery, chemotherapy, radiation therapy, and cryotherapy. These approaches may be administered individually, in various combinations, and/or in succession. Often, a combination of cancer treatment approaches yields the most effective results.
Each cancer treatment option has positive aspects and drawbacks. For example, radiation therapy, which uses high-energy rays or particles to destroy cancer cells, can damage nearby healthy tissue along with the cancer cells because it is difficult to administer accurately. Chemotherapy, which uses drugs to kill cancer cells, is also difficult to administer accurately and locally because chemotherapy drugs are toxic to both normal and cancerous cells.
Radiation therapy is a primary cancer treatment. It can be administered externally or internally. Externally, radiation may be administered via external beam therapy (EBT), in which high-energy x-ray beams are directed at the tumor from outside the body. Internally, radiation may be administered via brachytherapy, in which one or more pellets or “seeds” of radioactive material are placed in, or adjacent to, a tumor.
A key feature of brachytherapy is that the irradiation is localized around the radiation source. Exposure to radiation of healthy tissues further away from the sources is therefore reduced. The result is the ability to use a higher total dose of radiation to treat a smaller area and in a shorter time than is possible with external radiation treatment.
Cryotherapy can be a particularly advantageous cancer treatment because it does not use radiation and is direct treatment that kills only the targeted tissue. Additionally, cryotherapy requires a small incision and causes less trauma. With cryotherapy, one or more thin needles are inserted into the tumor and the needles are cooled using extremely cold liquids or using high-pressure gas. The needles are cooled so as to form ice balls at the tips. These iceballs freeze and kill the tumor. Thus, the problems of irradiation are avoided.
Two common cancers that may be treated via brachytherapy and cryotherapy are prostate and breast cancer.
Conventional breast cancer treatment, for example, can include a surgical approach and an additional approach. First, a tumor is removed by surgery (a lumpectomy) followed by external radiation therapy. In recent years, there has been a trend to replace external radiation therapy with internal radiation therapy, like brachytherapy.
Brachytherapy, in the treatment of breast cancer, is performed by positioning a balloon in the void of the removed tumor, and then placing one or more radiation sources (seeds) in the balloon. Typically, the balloon is positioned once during surgery. Thereafter, the seed may be replaced or removed, as required. Accurate positioning of the source in the same place is important.
Cryotherapy and other emerging tumor ablation techniques are investigated as replacement to the surgical component (lumpectomy) in treatment of breast cancer. One challenge is that when the tumor is ablated rather than surgically removed, there is no room (void) for a brachytherapy balloon. Presently there is no brachytherapy solution for breast tumors that does not feature such a balloon.
Among the advantages of using a removable radioactive source in a balloon, rather than permanently implanting a radioactive source, is that higher radiation doses may be used.